rhing
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Posts posted by rhing
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Rich,
You're like a drug dealer. First the hook then the ramp up.
I'm more eager now than ever to receive the Sure TA2024 and the Sure TPA3110 inbound from eBay. You influenced me into buying the Sures to supplement the TDA72972 which you persuaded me to get .
Unfortunately, there are more projects than time. I just received two Anarchy tapped horn kits (see: https://community.klipsch.com/index.php?/topic/138019-25hz-tapped-horn/). After I steal time to complete those, I'll play with the Sure amps and compare them to my TDA7297s.
Guilty as charged. The Sure TPA3110D2 is a nice amp, but it does seem to induce noise with my ARC LS7 tube line stage. I will have to trouble shoot the system and determine the source, but I suspect it is the TPA3110 amp since it doesn't have an LC output filter.
BTW, nice horn kits. Please share your listening results.
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After listening to this amp, I have to say I am very impressed with this Sure TPA3110D2 amp board. I have to qualify this statement with the fact that I connected this amp to my Audio Research LS7 vacuum tube line stage preamp, since I do not have any spare 50kohm volume pots except the cheap stock volume pots that came with my two TDA7297 amps. I used the Audio Research preamp to handle volume control duties. At this point, I cannot make a direct apples-to-apples comparison between the Sure Class D amp and the TDA7297 Class A/B amp, but I will say that the combination I have been listening to sounds better, overall, than the TDA7297 in stock or modified form.
- More detailed or articulate
- Deeper and cleaner bass--less boomy
- Higher frequency extension
- More natural tonality
- Soundstage is comparable with a large, deep soundstage
- Greater dynamic range
I feel like I'm splitting hairs with this, but I do hear the difference with careful listening with music material that I am very familiar with. Using my Alan Parson's "Sound Check 2" test CD which has a series of 1/2 octave tones from 20Hz up to 20kHz, I could verify that the bass response is lower with the TPA3110D2 than with the TDA7297. With the TPA3110D2, I could hear down to 31.5Hz in my room. I don't hear this with the TDA7297. In fact, the bass seems to roll off around 45Hz. What the TDA7297 does do is it seems to have a stronger bass output between 80 and 120Hz, which can give the impression that the bass is stronger.
I still have to sort this out, but I do hear some low level background noise with the TPA3110D2. The noise disappears when I engage the MUTE on my LS7, which indicates that the output filter-less TPA3110D2 amp may be emitting some RFI that's affecting my preamp. I never hear this noise, or any for that matter, from the TDA7297 or my Dynakit Stereo 35 tube amp. If this is something that cannot be reduced/eliminated, then an amp module such as the Yuan Jing TPA3116D2 2.0 amp might be a better solution since it does have the LC output filter to minimize RFI.
I still have more testing and listening to do, but the Texas Instruments Class D-proponents are probably onto something really good with these Class D amps. The TPA3110D2, TPA3116D2, TPA3122D2 and other TI Class D amps are representative of newer Class D technology than the Tripath Class D technology, which hasn't been refined since Tripath went out of business. -
Beautiful plinth! What kind of wood is it made of?
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I would only put a balance pot on the amp if you absolutely need it. I refurbished a Dynaco SCA-35 and kept all the tone and balance controls. As it turned out, I didn't need them, and all these pots are lossy components that suck a bit of life out of the music. If you only plan to use the amp as a power amp, then try it out first as a power amp and add a volume pot or stepped attenuator as needed. With my TDA7297 amp used with my line stage preamp, I just turn the Alps Blue Velvet all the way up (0kohms) and it works fine, but I am sure the good quality of the Alps pot keeps any signal loss to a minimum.
As soon as my TPA3110D2 amp comes in, I will wire it up as a power amp and use my ARC LS7 line stage to control volume. I am really interested to see if this Class D amp has the headroom of the TDA7297. The TDA7297 casts a really large soundstage that rivaled my tube amps. -
I had a holiday audio get together at my home yesterday comparing the TDA7297 chip amp to my restored and EFB-modified Dynakit Stereo 35 6BQ5/EL84 push-pull amp. Actually, it was a comparison between the TDA7297 and the combination of my Audio Research LS7 tube line stage and Dynakit Stereo 35. I ran the TDA7297 as an integrated amp. I kind of had my Stereo 35 and TDA7297 amps tucked away behind the Klispch Forte II speaker on the right hand side.
My friend John has been applying some system set-up tips from Jim Smith's "Get Better Sound" (Quarter Note Press) to speaker placement and room treatments, so he brought over his book and we played around with speaker placement and throwing large, thick beach towels over my LCD TV and glass-top coffee table in my living room. These tweaks made profound improvements, and I encourage anyone who cares about great sound quality to invest in this book.
My friends and I enjoyed quite a few nice LPs:- Paul Motian Trio, Le Voyage, ECM
- Kenny Drew, Freddie Hubbard, Hank Mobley et al, Undercurrent, Blue Note (Music Matters reissue)
- Tina Brooks, True Blue, Blue Note (Music Matters reissue)
- Muddy Waters, Folk Singer, Chess (Classic Recordings reissue)
- Pink Floyd, Wish You Were Here, EMI (reissue)
Not surprisingly, the vacuum tube amp combination won out, but not by much. The tube amps were slightly more detailed and created a slightly more three dimensional presentation. My friends liked the ability to hear the better defined separation of performers in the soundstage. Interestingly, the tube amps had a more forward presentation than the TDA7297.
My friends knew nothing about the TD7297 chip amp before the get together, so they were quite astonished by the small size of the amp and the big sounds they heard from it. They all agreed that the TDA7297 has a warm tube-like presentation, impressive dynamic response and a well defined low end. The imaging was bit more diffused compared to the tube amps. It is analogous to using a diffuser in film.
I told my friends that I have the Sure Electronics TPA3110D2 Class D amp from Parts Express on its way, and that we would have to have another amp shoot-out soon. Anyway, everyone really liked the TDA7297 and I get the feeling that my friends will placing orders on eBay soon.-
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Very nice work indeed. I would love to get a good deal on a Dual 1019 or Dual 1229 and refurbish it. I think these are very nice idler wheel drive turntables. I have many fond memories growing up and hearing my uncles playing LPs on their Dual turntables.
Check the condition of the bearings if the TT needs to be re-lubed. A good soak and cleaning of moving parts in lighter fluid always helps. Also, use the recommended lubricants.
I did a complete teardown, clean-up, re-lube and rebuild of this Kenwood PC-400U belt-idler wheel drive turntable from the late-1960s. The bearing thrust plates were shot and I fabricated new ones from high wear, low friction Delrin (white discs). I used metal polishing compound to polish the spindles and bearings for the platter and the idler wheel. I used Rubber Renew on the rubber idler wheel to get it nice and rubbery again. I also rebuilt the original, stock Jelco SA-100 tonearm and rewired it using Cardas 33 gauge tonearm wire. The turntable is built a lot like a Thorens TD124, and now serves as my main turntable--lots of that good idler wheel magic.
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Thanks for posting the link. The music sounded so good, I must have been distracted. The great thing about the TPA3110D2 amp is that it will run on the same power supplies that work with the TDA7297. I've included the Sure Electronics manual for this amplifier.
320-329-Parts-Express-Brochure, Sure Electronics TPA3110D2.pdf
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This TDA7297 is sounding really nice with my vinyl playback system, but I'm now getting that itch to explore the Texas Instruments TPA-31xx Class D amps. There's a rather lengthy thread on the diyAudio Class D forum about the TPA3118D2 amp boards from Yuan Jing, a Chinese manufacturer of low cost hi if electronics. Like the TDA7297 chip amp, these newer generation Class D amps are claimed to sound better than Tripath T-amps. For $10, it's a cheap experiment, and I can use my wood test rig to wire up the TPA3110 board and connect it to my Forte II amps.
A friend also donated a Magnavox console amp that is a single ended pentode 6BQ5/EL84 stereo amplifier. It looks like I'll have some experimentation this holiday season comparing low powered SS and tube amps. -
I took my first prototype TDA7297 chip amp with the Mundorf Supreme coupling caps and installed it in a nice black anodized, brushed Aluminum enclosure that I picked up at a Fry's Electronics store. Fry's is a chain of electronic superstores out in the West Coast. Each store is about the size of a Walmart and they carry everything electronic under the sun. Anyway, the Context Engineering extruded Aluminum case cost me $25 including tax. I spent most of the morning drilling all the holes for the connectors, ventilation and Alps Blue Velvet volume pot. Eventually, I will design a thick Silver brushed Aluminum faceplate that will match my ARC gear and order it from Front Panel Express. I also installed a mini toggle SPST on/off switch that I picked up from Radio Shack. The knob is from a Chinese eBay seller. It's no longer a $6 bargain chip amp, but for about $125, I have a nice sounding little black box.
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That's really cool. I was listening to some vinyl as well with my PH5 phono stage connected to my second TDA7297 amp with the Black Gate N caps. My Talisman Alchemist IIB is a high output MC cartridge as well. With this amp's largish soundstage, vinyl playback creates a life-size image in my man cave. The sound extends well beyond the space between my speakers. I'm planning an audio get together at my home in a week, and I'm going to have my audio buddies compare the TDA7297 amp to my SMSL SA-S1 TA2020 T-amp and the combination of the ARC LS7 line stage and Dynakit Stereo 35. The guys will be blindfolded, so their listening impressions will be unbiased.
I'm glad the Wima MKP2 caps are working out for you. I used these in a Dynaco SCA-35 restoration, and I was really impressed with Wima MKP caps in the phono stage and driver stage in the Dynaco amp. If you haven't already, try the Dave Brubeck Quartet's "Time Out" or Sonny Rollins' "Saxaphone Colossus" through your set up. Piano sounds great through this amp as well. You can put anything by Bill Evans on.
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Just enjoy the music. I wear safety goggles when I solder, but I can still see well without my glasses.
I forgot to list wire in my parts lists.
For the connections from the board to the speaker binding posts, I use 19AWG Kimber TCSS Teflon-insulated stranded Copper wire.
For the connections between the RCA connectors, I use Mil-Spec 20AWG Teflon-insulated Silver-plated Copper solid core wire. Sometimes, I use 0.5mm Mundorf Teflon-wrapped Silver/Gold solid core wire for signal connections.
For the DC power connection, I use Mil-Spec 20AWG Teflon-insulated Silver-plated Copper stranded wire.
I always use Cardas 2% Silver quad-eutectic solder. To me, this is the best solder for audio projects. Enid Lumley of The Absolute Sound magazine conducted a test years ago comparing solder compounds by making speaker wire purely out of solder. In her final analysis, the Cardas QES won out as being the most transparent-sounding solder.
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Can you draw up a schematic that a layman can understand. I would like to retain the original pc board for the visual effect. I am going to use two boards to mount everything like you did in post 170. I already have two of the amps that just arrived Wednesday. Thanks, Bill
I have assembled a diagram for the TDA7297 amplifier connections. This corresponds to the TDA7297 amp I purchased from eBay seller homemart.usa. Other amp modules may differ in their layouts and connections. I have also assembled a Bill of Materials (i.e., BOM or parts list) for anyone who is interested in upgrading the parts of their TDA7297 amp. I upgraded my second amp with 1uF / 50V Black Gate N caps. These are near-unobtainium, but Sonic Craft still has some in stock. To my ears, these are comparable to the Mundorf Supreme caps I installed in my first unit. The Elna Silmic IIs, the Wima MKP2 and the Black Gate N caps will all fit on the board. Notice, the cost of the $6 amp does increase considerably, and some people may think my BOMs are overkill, but I'm enjoying these upgrades and this amp is still performing at an astounding performance-to-price ratio.
Now that the USPS finally delivered my TC-760LC phono preamp posted by billybob weeks ago, I'm in a position to listen to vinyl being played through my chip amps. As an aside, I couldn't be more pleased with the TC-760LC.
The attached photo shows my test bench (my late mother would be mortified, if she weren't already mortified, to see the family piano used as a test bench). On the right is the stock TDA7297 (the 2nd one received, which sounded better than #1). On the left is the modified TDA7297. Each amp has spikes from the barrier strip to which alligator clips can be sued for quick change connections to speakers. The modded amp has alligator clips to permit quickly switching between coupling caps.
The modifications, in the order performed, as suggested by Rick, aka rhing, to date are:
- Replacing the stock Chang 2,200 uf 25v power supply cap with larger Panasonic version;
- Removing the volume pot;
- Removing stock coupling caps; and
- Inserting either WIMA; or
- Panasonic coupling caps.
After limited listening, I'm ready to state the following:
- The modified amp now sounds markedly better than the stock amp;
- The most significant improvement followed the the upgraded power supply cap;
- the other modifications produced real, but more subtle improvements;
- My 65 y.o. ears cannot discern a significant difference between the WIMA or Panasonic coupling caps; and
- the cumulative results of all mods (using either WIMA or Panasonic coupling caps) seem greater than the sum of the parts.
Subjectively, the bass is tighter and the sound seems more 3D with the modified amp. A strength of the TDA7297 is the ability to reproduce the sound of horns, whether sax or brass. That quality is enhanced by the mods.
If interested, the photo also shows the Dynaco QD-1 (which Dave Mallete tempted me to get) and the TC-760LC. The TDA7292s and QD-1 are sitting on a Dynaco FM-5. The barrier strips behind the QD-1 enable easier and more secure connections to the QD-1. The spacing of 12 thumb-screw terminals on the rear of the QD-1 makes connections difficult and unstable. The thumb-screws were replaced by slotted screws that can be more easily and securely tightened. Short leads from the QD-1 to the barrier strips allow for adding or subtracting components easily without disturbing the antique terminals on the QD-1. Dave Mallete knows what I mean.
I accidentally ordered 4 of the Panasonic power supply caps. Also there will be four "upgrade" coupling caps available, when the smoke clears. If anyone is interested, they're your's for the cost to ship.
As part of my new vinyl addiction, I ordered a Denon DL-110 MC cartridge. It'll be my first experience with MC. I was seduced by the price ($139 from Amazon) and favorable reviews, especially the one attached. I was especially intrigued by the predicted suitability for enjoying used records, how I feed my addiction.
Nice test rig. I really like that experimental test bench look. Actually, I am glad to hear that the Wima MKP2 caps are comparable to the Panasonic ECQP caps. They are less expensive and these should fit right onto the board to keep things neat and clean.
Your listening impressions follow mine. The 2,200uF / 25V Panasonic FM electrolytic cap in the power supply path makes a profound difference in dynamic response, bass definition and the size of the soundstage. Better input caps do reveal more detail and a slight improvement in tonality.
Thanks for sharing about the Denon MC cartridge. I may have to get one of these for my restored Kenwood PC-400U belt/idler wheel drive turntable. I have a Talisman Alchemist 2B high output MC cartridge that is a bit long in the tooth, and probably needs to be re-tipped and/or replaced.
TDA7297 Bill of Materials, Elna Silmic II Caps.pdf
TDA7297 Bill of Materials, Wima MKP Caps.pdf
TDA7297 Bill of Materials, Black Gate N Caps.pdf
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Hi Bill,
PM me and I can go over the details of what you need.
Rich
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Try Jim McShane. I buy my matched tubes and parts from him for my restore projects. He's very responsive and he wants to make sure he understands the sound quality you are looking for. I've never been disappointed in his recommendations. Just Google "Jim McShane tubes" and you'll find him.
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Ask the seller if he has the original boxes. If he doesn't, offer $600 and negotiate from there. They do look nice.
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If you look at my Avatar, you can see I use a Peavey FH-1 (cheaper and more ruggedly built than old LaScala cabs). Inside, I have EVM-15L woofers with brand new recones using OEM parts.
I'm driving this bass horn with a strock $22 Lepai from Parts Express being bandpasse filterered by a Behringer DCX-2496 because I hate inductors. DizRotus heard it when I was still in Michigan........FYI
Claude,
I would love to listen to your speaker setup. I am a Michigan native too, and I now live in California, and my home isn't large enough to accommodate an array like yours. I love big, efficient horn-based speakers like Klipsch and Altec Lansing speakers. My dream set is a pair of Altec Lansing Model 19s or Klipschorns, but your speakers might trounce them.
Anyway, I would encourage you to try this TDA7297 chip amp to drive your bass horns. You can use the same power supply that you use with the Lepai and you'll get lower distortion and greater headroom assuming your bass horns are a nominal 8 ohm load. Unlike Class D amps like the Lepai TA2020, there is no high frequency switching noise to filter out with an output filter consisting of inductors and multiple capacitors. The output is straight from the transistors in the chip itself. The input just has the two capacitors.
I think the TA2020 Tripath is the cream of the Tripath crop of T-amps, and that's why I bought an SMSL SA-S1. I've tried other T-amps like the Sonic Impact 5065 Gen 2 (TA2024, which I modded), and the Virtue Audio 2 (TK2050), but the SMSL SA-S1 amp beat those hands-down. I think a modded Lepai TA2020 would be comparable to the SMSL amp, but this TDA7297 in stock form is better yet, especially in the lower frequencies. With additional low-budget mods like what I recommended to DizRotus, this amp goes to another level of performance.
These amps haven't hit these shores yet, but now a Chinese manufacturer is coupling a tube input buffer with the TDA7297 chip amp:
I have no idea how they came up with this odd name, but it's probably a decent sounding amp with that tube providing some warmth.
Happy Thanksgiving!
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Here is my second TDA7297 chip amp that I mounted on a makeshift chassis using scrap wood pieces I still haven't hooked up the RCA jacks directly to the amp circuit board, because I just wanted to hear how it sounds in complete stock form. Surprisingly, it sounds very good. My first unit, which I upgraded with Mundorf Supreme film caps had a high-mid/treble glare with the stock orange Polyester film caps. This unit sounds more tonally balanced. I can only reason that:
- The quality of the stock components is not consistent, or
- The RCA-to-mini-stereo jack cable is attenuating the glare and creating tonal balance.
I'll keep this around as a loaner so some of my other local audio friends can audition this unit on their own.
One thing is certain in that this little chip amp, even in stock form, outperforms my SMSL SA-S1 Tripath TA2020 T-amp. I still really like SMSL amp, but this TDA7297 creates a larger, deeper soundstage, has a noticeably cleaner midrange and treble, greater headroom and a more focused image.
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Glad to hear that people are happy with their TDA7297 amps. I had also purchased a second TDA7297 amp module to keep in stock form for a little while. I will need to draw on my memory to determine if there is any variation in the units. Keep in mind that the manufacturer, whoever it may be in China, is using cheap solder and the volume pots aren't the greatest quality either, so it would almost be surprising if the amps are consistent from unit-to-unit. I'll end up upgrading the second unit with better parts, but keep the costs down in the spirit of less-is-more audio.
These amps are so small you can get creative with an enclosure. One guy even boxed it in a neat little black cardboard box. Some people have used wood cigar boxes. It basically comes down to your DIY skills. Maybe someone should use Lego blocks. My plan is to put my upgraded-version into a black-anodized Aluminum enclosure.
Here's my friend's temporary setup. He used the Mundorf Supreme caps as well. Hi spower supply is the Mean Well RS-100-12 100 watt SMPS.
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Hmmmmm at $6 what the heck..... Pass on the info sounds like fun. How did you modify it? Yeah the adcom is old and basically it was a donation as well. I just have to figure out what I move to next. As i said earlier Im a fan of Mr. Pass but even on the used market his stuff is a bit out of my price range probably. Ive had my eye on a couple emotive mono blocks in my area. I've been happy with my umc-1 from them.
You can read about the STM TDA7297 Class AB chip amp module on this Klipsch forum thread:
https://community.klipsch.com/index.php?/topic/144613-chip-amps/?p=1664366
I have chronicled my mods/upgrades on that thread. I originally found out about this amp through the diyAudio.com forum:
http://www.diyaudio.com/forums/class-d/231988-what-heck-its-less-than-lunch.html
What caught my attention in the diyAudio forum thread was that the guy who started the thread owns a pair of La Scalas.
If you search the auction Web site using "tda7297f," you will find several listings for this amp module. I bought mine from the seller "homemart.usa" who ironically is located in Hong Kong, but there are others. You will need a laptop-type power supply capable of 12V and 2A output. The amp can take up to 18V, but try to keep it less than 16V and keep the current output above 2A. The amp will take a higher current of 5A to 8A. The DC power input jack is a 2.1mm x 5.5mm DC power jack. With upgrading the input capacitors and the power supply cap, anyone with high sensitivity speakers like Cornwalls can get a rich full sound with deep bass.
This is not a Class D amp, but a Class AB chip amp that has hardly anything in the signal path, but the two input caps. A friend in another part of the country who also owns Forte IIs tried this amp out and he is using this as his main amp as he channels his funds to upgrading his Forte II crossovers. When he completed some simple upgrades, he and his wife stayed up until 3 AM listening to music one Saturday evening. She's a musician with perfect pitch and she told me the tonality of this amp was great with excellent bass response. With a decent power supply, the amp is dead silent, so noise is not a factor. I have friends here in the Bay Area with Klipschorns and Altec Lansing Model 19s that I will audition with this little amp. I was skeptical about this amp myself when I first read about it, but I've wasted $6 on bad lunches and audio parts. It's a great way to enjoy your new Cornwalls with quality amplification without breaking the bank.
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Congratulations on your Cornwall IIs. After I purchased my Forte IIs, I contacted Bob Crites about two months later for his Titanium tweeter diaphragms, crossover cap upgrade kit and new internal wiring for my speakers. I also installed better Pomona 3770 Gold-plated Copper 5-way binding posts. To my ears, I feel like I have retained the original character of the Forte IIs while making refinements that make these speakers really high end. I may opt for the Titanium midrange diaphragms from Klipsch that many have raved about as well.
As far as amps go, good amps will sound good with Klipsch Heritage speakers--tubes or solid state. Bad amps won't sound good, because the high sensitivity of Klipsch speakers will expose them, flaws and all. I have an Audio Research phono stage, an Audio Research line stage and a restored/modified Dynakit Stereo 35 6BQ5/EL84 amp that sound great through my Forte IIs, but lately I've been having fun with a $6 15 watt chip amp that I've upgraded with better components that beats a modified Adcom GFA-535 a friend donated to me. The little 15 watt amp still does not sound as good as my tube amp setup, but it isn't too far behind either. A friend of mine is bringing his 300B SET monoblocks over to have a shootout with the chip amp and my tube amps. this will be fun.
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billybob,
Be prepared to do some modding to get that amp sounding its best. There are numerous forum threads about modifying them. Once modded, these amps can sound really good.
Rich
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Rhing...
How go you remove enough solder to remove the jacks that come with the board? I've tried a wick, but couldn't get enough off to free the jacks.
Mike
Hi Mike,
I use a solder sucker tool from Radio Shack. It looks like a large syringe that has a spring loaded device to instantly suck solder once it reflows. A couple of hits on each contact, and the volume pot and 1/8" mini-stereo jack both fell off the board easily. For working on printed circuit boards from China, I've found they typically use a cheap solder that does not flow well, so using a wick is almost impossible to use to clean up solder. On top of that, the traces and eyelets on the boards aren't very sturdy and have a tendency to peel off the board after prolonged heating from solder iron contact.
Rich,
I overlooked your questions about my use of a Car Start CS1000. The amp doesn't smoke or get warm when powered by the CS1000. The amp is currently driving four DIY single driver BR enclosures similar to discontinued Tekton 3.1 (see: https://community.klipsch.com/index.php?/topic/56494-single-driver-experiments/) used with a Dynaco QD-1, thank's to Dave Mallette's thread. (see https://community.klipsch.com/index.php?/topic/145727-quadapter-back-yay/). Due to attachment limitations in the new forum, attachments have been deleted from older threads. A photo of one of the speakers is attached.
As expected, the bass is not prodigious from these small BR enclosures. Nonetheless, the quality of the available bass is clearly improved with the CS1000 over several 12v bricks from 2A - 6A. I plan to try these with some DIY KEF B139 transmission line subs I use to augment LS3/5as for the TV, just out of curiosity, not as a serious permanent solution.
Until my newly purchased (and much traveled) phono preamp finally arrives from billybob, my only source for the chip amps is Pandora or mp3s via Bluetooth. Serious experimentation and comparisons will be made after a turntable can be added to the mix.
It's probably buried deeper in this thread, but I'd appreciate more info regarding the source of the stepped attenuator you're using.
This TDA7297 is starting to be "Stone Soup."
If you search for "smt stepped attenuator" or "stepped attenuator" on eBay, you'll find a bunch of stepped attenuators from sellers "lasercollection" and "tube_buyer." These are identical products, and lasercollection's description is very thorough on explaining the value and design of the product. I would recommend the 50k SMT stepped attenuator with the logarithmic taper for this amp. You could go to a 25k stepped attenuator, but you'd probably have to use higher capacitance input coupling caps (i.e., 0.47uF) to maintain the same tonality. If you want to reduce output (i.e., too loud), you can use a 100k stepped attenuator.
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While I was out of town on business this past week, my 50k, log tapered SMD resistor-type stepped attenuator came in from auction seller tube_buyer. I had an L-bracket in my stash from a volume control extension kit that I used to mount the stepped attenuator. I directly wired the RCA input jacks, the two Mundorf input capacitors and the ground connections to the stepped attenuator. The other ends of the Mundorf caps were connected to the amp PCB where the old caps were mounted. So now this amp is 50% point-to-point wired.
The sound is clearer with the stepped attenuator and balanced from silence to high volumes. It actually plays slightly louder since most of the signal path uses high quality wire instead of thin Copper traces on a PCB. I am very pleased with this amp driving my Klipsch Forte IIs. It doesn't have the full bloom and tonality of my Audio Research LS7 line stage and Dynakit Stereo 35 tube amp combination, but it does present big sound with a wide and deep soundstage, and at a significantly lower cost. At this point, I am going to install this amplifier in a permanent, compact Aluminum enclosure available from auction seller, fan_computer, for $18. Adding up the costs of all the parts I've pieced together including the enclosure, my total comes to $130. For a low power integrated amplifier, this amp can run with some serious gear and free up cash to buy great-sounding, efficient speakers like Klipsch Heritage speakers.
Now to add more to the chip amp fun, I've been egged on by diyAudio.com forum members to explore Texas Instruments' TPA3116D2 Class D amp.
http://www.diyaudio.com/forums/class-d/237086-tpa3116d2-amp.html
A Chinese manufacturer, Yuan Jing, makes an amp module using this Class D chip. This is a higher power amplifier (50W) that even tube amp builders are falling for. This newer Class D amp is supposed to easily eclipse the older Tripath amps. The saga continues ...
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Hi
I ordered a pair of these TDA7297 amps, just for fun. I also have a TA2020 amp that I run from a 18AH 12 volt battery. I did notice an increase in bass response over the SMPS. I'll use the battery on the TDA7297 amps when they arrive.
Do the TDA7297 amps have on/off thumps?
I'll probably try these on my bi-amped Khorns, replacing the SET amps.
Thanks, Mike
Hi Mike,
The battery should work fine. Here's a simple calculation you can use for the battery charge life:
Power [watt] = Voltage [Volt] x Current [Amp], or
P = V x I
=> Current [Amp] = Power [watt] / Voltage [Volt],
=> Current [Amp] = 15W / 12V = 1.25A
and
=> Time[h] = Capacity[Ah] / Current[Amp]
=> Time[h] = 18Ah / 1.25A = 18h
This is an approximation at best assuming no losses occur and that the amp is driven at 15W, which we know is not the case.
As for the turn-on/turn-off thump, I haven't put a power switch in place between the amp and SMPS. When I plug in the amp, there is no thump. When I unplug the amp, I hear a small thump, but nothing that is objectionably loud or cause for damage. I actually leave the amp on for several days, and I haven't had any problems yet.
Please share your listening impressions.
chip amps: Almost everything you ever wanted to know
in 2-Channel Home Audio
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Okay guys, I was able to sort out a solution to significantly reducing the noise. I wired 33kohm resistors between the signal input and signal ground on each channel. Now that I am able to listen to this amp, I have to say I am impressed with this amp driving my Forte II's. I will probably have to sell my TDA7297 and SMSL SA-S1 amplifiers. This little amp is the real deal. Before you think about buying the Sure TPA3110D2 amp, consider the Yuan Jing TPA3116D2 Class D amp. This amp is based on the newer, more powerful Texas Instruments TPA3116D2 amp and it has output filters to minimize RFI from the switching amp chip circuit.
In hindsight, I wish I bought the Yuan Jing board, but I'm happy with this little guy for now. One thing is certain, this amp clearly outperforms any Tripath amp I've owned. It is absolutely void of any glare and tilted treble synonymous with Class D amps, and it has a serious low end and large soundstage. If anything, it is smoother and more transparent than the TDA7297 chip amp and Tripath TA2020 or TA2024 amps I've owned. I'm listening to Patricia Barber's "Cafe Blue," and the kick drum is presented in full note-form and thumping the floor. The tonality and detail are something to behold. The real kicker is that I don't have to mod this amp other than add those resistors or a 50kohm volume pot at the inputs. This amp sounds great out of the box.